The invention relates to a device for the electrically conducting contacting of an electrically conducting part of an outer surface of a tube, a cable, or the like, in particular a coaxial cable""s outer conductor bared in sections.
A device of the relevant type is known through EP 0 744 788 A1. It has a body abutting in the mounted position the element to be contacted, the body consisting of a metallic clamp band which is coated with an elastic material which is formed by rubber.
According to the invention the elastic material consists of at least one at least partially vulcanized ethylene-propylene rubber. Through the use of such an ethylene-propylene rubber the device according to the invention surprisingly obtains advantageous mechanical characteristics. Thus the elastic material of the body obtains a particularly high tensile strength over a wide range of material hardness. Moreover, the elastic material of the body is particularly resistant to ozone, weathering, and chemical influences. Furthermore, the elastic material of the body has outstanding electrical insulation characteristics. The compression set, the temperature resistance, and the flexibility at low temperatures can be chosen as a function of the formulation and the polymer composition or polymer mixture within wide limits.
The degree of vulcanization of the ethylene-propylene rubber can vary according to the conditions at hand.
The elastic material of the body can contain a single type of ethylene-propylene rubber. However, it can also contain several types of ethylene-propylene rubber.
A particularly advantageous extension of the teaching according to the invention provides that the elastic material of the body contains a mixture (blend) at least of one ethylene-propylene rubber with at least one thermoplastic elastomer (TPE). Thermoplastic elastomers have characteristics similar to plastic and are easy to process. For example, the body, in so far as it consists of the elastic material, can be produced with the use of thermoplastic elastomers in an injection process.
Surprisingly it has proven itself advantageous if the ethylene-propylene rubber is EPDM. In the case of this form of embodiment particularly advantageous mechanical characteristics result.
The body of the device according to the invention can in principle be formed rigidly. An expedient extension provides that the body is formed flexibly. In the case of this form of embodiment the body adapts itself, due to its flexibility, to the surface of the element to be contacted. This makes possible contacting even of very uneven or curved elements.
Another extension provides that the body is formed in such a way that it engages around the element to be contacted, preferably in the form of a ring or sleeve, in the mounted position. For example, in the case of the contacting of tubes or cables the body is held securely in this manner on the element to be contacted.
Another expedient form of embodiment provides that the body is formed as a clamp which can be tightened about the element to be contacted. In the case of this form of embodiment the mounting of the device according to the invention is simplified.
The body of the device according to the invention can be formed of multiple parts, for example for the contacting a tube or cable by several parts, for example in the form of a half rings, following one after the other in the circumferential direction in the mounted position. It is however advantageous if the body is formed as one part and has at its free ends tongues angled or bent off which can be connected to one another in the mounted position, preferably by means of a screw device or a clamping device. Due to the one-part formation of the body the mounting of the device according to the invention is further simplified in the case of this form of embodiment. By connecting the tongues to one another the device can be fastened in a rapid and simple manner to the element to be contacted.
Another advantageous form of embodiment provides that the device has sealing means for the sealing of a space formed in the mounted position between the element to be contacted and the body against the penetration of air and/or humidity. In this way it is prevented that humidity penetrates into a contact area in which the device contacts the electrically conducting part of the element to be contacted.
Another extension of the aforementioned form of embodiment provides that the sealing means has sealing lips of an elastic material, spaced from one another in the axial direction of the body, and extending in the circumferential direction of the body, said sealing lips being disposed on a side of the body facing the element to be contacted in the mounted position and in the mounted position sealingly abutting the outer surface of the element to be contacted. In this way one achieves a seal against penetration by air, dust, or humidity of the space formed in the mounted position between the element to be contacted and the body. In the case of the aforementioned form of embodiment the elastic material of the sealing lips expediently contains at least one thermoplastic elastomer and/or at least one at least partially vulcanized ethylene-propylene rubber, in particular EPDM.
An advantageous extension of the aforementioned form of embodiment provides that the sealing lips consist of the same elastic material as the body, in particular are formed as one piece with the elastic material of the body. In this way the production of the device according to the invention is further simplified.
According to one form of embodiment the elastic material of the body has at least one of the following material characteristics:
the Shore hardness (A) is between 35 and 85, preferably between 47 and 70, in particular approximately 64 (DIN 53505-A [DIN=Deutsches Institut fxc3xcr Normung=German Institute for Standardization]),
the tensile strength is more than approximately 6 MPa (DIN 53540),
the elongation at tearing is more than approximately 300% (DIN 53504),
the elastic material is ozone-resistant and/or UV-resistant and/or oil-resistant and/or weather-resistant.
In principle the body can consist entirely of an elastic material. An advantageous extension provides however that the body has a carrier element to which the elastic material is connected. In this way the stability of the device according to the invention is increased.
An extension of the aforementioned form of embodiment provides that the carrier element is formed essentially in the form of a band and extends in the longitudinal direction or in the circumferential direction of the body preferably over its entire length and preferably forms the tongues. This form of embodiment is particularly simple in construction and thus can be produced cost-effectively.
In the case of the forms of embodiment with the carrier element it consists preferably of metal, in particular of brass and/or special brass and/or slightly alloyed copper and/or chromium/nickel alloyed steel. These materials have a particularly good electrical conductivity.
Expediently the contact means have a contact element which is disposed on a side of the body facing the element to be contacted in the mounted position and is connected to it.
Extensions of the forms of embodiment with the contact element provide that the contact element consists of metal, preferably being formed by a flat litz wire, a flat band, or a braided band of metal. Contact elements of this type are cost-effective.
Expediently the contact element is connected to the carrier element. If the carrier element consists of metal, then, by producing an electrical conducting connection between a conductor, for example a grounding cable, and the carrier element, which can be accessible from outside in the mounted position, an electrically conducting connection to the element to be contacted can be produced via the contact element abutting the element to be contacted.
Another extension provides that the body-has at least one contact projection of electrically conducting-material which in the mounted position abuts the electrically conducting part of the element to be contacted and thus forms the contact means. In the case of this form of embodiment a separate contact element is not required so that the device according to the invention is further simplified in its construction.
In the case of the aforementioned form of embodiment each contact projection is expediently formed on the carrier element. If this consists, for example, of sheet metal, then the contact projections can be formed by beads or arches pressed into the sheet metal.